Method of depositing silicon oxide films

ABSTRACT

Methods of depositing a silicon oxide film are disclosed. One embodiment is a plasma enhanced atomic layer deposition (PEALD) process that includes supplying a vapor phase silicon precursor, such as a diaminosilane compound, to a substrate, and supplying oxygen plasma to the substrate. Another embodiment is a pulsed hybrid method between atomic layer deposition (ALD) and chemical vapor deposition (CVD). In the other embodiment, a vapor phase silicon precursor, such as a diaminosilane compound, is supplied to a substrate while ozone gas is continuously or discontinuously supplied to the substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(a) to and thebenefit of Korean Patent Application No. 10-2007-0080581 filed in theKorean Intellectual Property Office on Aug. 10, 2007, the entiredisclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to deposition of thin films. Moreparticularly, the present invention relates to a method of depositingsilicon oxide films.

2. Description of the Related Art

In depositing silicon oxide films for semiconductor devices, chemicalvapor deposition (CVD) methods, such as low pressure CVD (LPCVD),atmospheric pressure CVD (APCVD), and plasma-enhanced CVD (PECVD), havebeen widely used. In LPCVD or APCVD, two or more source gases can besimultaneously supplied and deposited at a relatively high temperature(for example, about 500° C. to about 850° C.) to form a silicon oxidefilm over a substrate. In PECVD, a mixture of a vapor-phase precursorand a reactant gas can be activated by plasma to form a silicon oxidefilm.

Silicon oxide films deposited by a high temperature CVD process, such asLPCVD or APCVD, tend to have defects, such as interface oxidation anddopant diffusion. Such defects may degrade electrical characteristics ofdevices that include the silicon oxide films. Silicon oxide filmsdeposited by a PECVD process may include about 2 atomic % to about 9atomic % of hydrogen and nitrogen atoms. Such hydrogen and nitrogenatoms in the films may adversely affect the processing of the films, andresult in a deviated refractive index (RI) and inconsistent etchselectivity.

Recently, the circuit density of semiconductor devices has beenincreased while the geometry of circuits has been decreased. Inaddition, aspect ratios of features in semiconductor devices have beenincreased. Accordingly, there is a need for a method of depositingsilicon oxide films having enhanced step coverage over features of highaspect ratios, particularly for films that are thin and/or uniformlythick.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention, anddoes not constitute prior art.

SUMMARY OF THE INVENTION

According to one embodiment, a method of depositing a silicon oxide filmover a substrate is provided. The method includes one or more ofdeposition cycles. Each of the cycles includes: supplying a plurality ofpulses of silicon source gas of a compound represented by Formula 1 intoa reactor in which a substrate is loaded.

R is a straight or branched alkyl group having 1 to 4 carbons. Themethod also includes providing an oxygen-containing gas over thesubstrate in the reactor.

According to another embodiment, an apparatus includes a silicon oxidefilm made by the method described above. The silicon oxide film has anatomic ratio of silicon to oxygen of about 1:1, and the silicon oxidefilm has a refractive index between about 1.459 and about 1.483.

According to yet another embodiment, a method of forming a thin filmover a substrate is provided. The method includes a first cycle whichcomprises: supplying a vapor phase silicon precursor comprisingdiaminosilane over a substrate; purging the vapor phase siliconprecursor from the substrate; and supplying ozone gas to the substrateduring supplying the vapor phase silicon precursor and after purging andbefore a subsequent cycle.

According to yet another embodiment, a method of depositing a thin filmover a substrate is provided. The method includes supplying a siliconsource gas to a substrate; and supplying an excited oxygen species tothe substrate to form a film, such that the film has an atomic ratio ofSi to O of about 0.5:1 to about 1.1:1.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart illustrating a method of depositing a siliconoxide film according to a first embodiment.

FIG. 2 is a graph illustrating the atomic emission spectroscopy (AES)analysis results of a silicon oxide film deposited by a method accordingto the first embodiment.

FIG. 3 is a graph illustrating the refractive indices (RI) of siliconoxide films formed by deposition methods according to the firstembodiment and other methods for comparison

FIG. 4 is a timing diagram illustrating a method of depositing a siliconoxide film according to a second embodiment.

FIG. 5 is a wafer map illustrating uniformity of a silicon oxide filmdeposited by a method according to the second embodiment.

FIG. 6 is a wafer map illustrating the thickness uniformity of a siliconoxide film deposited by a method according to the first embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsof the invention are shown. As those skilled in the art would realize,the described embodiments may be modified in various different ways, allwithout departing from the spirit or scope of the invention.

A method of depositing a silicon oxide film according to a firstembodiment will be described with reference to FIG. 1. FIG. 1 is aflowchart illustrating a cyclical method of depositing a silicon oxidefilm.

First, a substrate on which a silicon oxide film is to be deposited isloaded into a reactor (step 100). In one embodiment, the substrate maybe a wafer formed of silicon. In other embodiments, the substrate may beformed of any other suitable material. The substrate may include one ormore layers or features (for example, lines, islands, trenches, etc.)formed thereon.

In one embodiment, the reactor may be a chemical vapor deposition (CVD)reactor. In another embodiment, the reactor may be an atomic layerdeposition (ALD) reactor. Examples of reactors include, but are notlimited to, those described in U.S. Pat. No. 6,539,891; U.S. Pat. No.6,645,574; U.S. Patent Application Publication No. 2005/0034664; U.S.Patent Application Publication No. 2006/0249077; and U.S. PatentApplication Publication No. 2007/0215036, the disclosures of which areincorporated herein by reference in their entireties. ALD reactors areoptimized for fast switching among purge gases and reactant gases, andto keep mutually reactive reactants separate from one another in the gasphase. A skilled artisan will appreciate that any suitable reactor maybe adapted for the method.

Next, a gas-phase precursor is supplied over the substrate (step 110) inthe reactor. In one embodiment, the precursor may include adiaminosilane compound represented by Formula 1 below.

In Formula 1, R is a straight or branched alkyl group having 1 to 4carbons (R═C_(n)H_(2n+1); n is an integer of 1 to 4). In one embodiment,the precursor may be N,N,N′,N′-tetraethyldiaminosilane which can berepresented by the chemical formula, SiH₂[N(C₂H₅)₂]₂. The precursor maybe supplied at a vapor pressure of about 2 torr at room temperature.

Next, a purge gas, such as Ar, is supplied (step 120) into the reactorto purge the reactor. A skilled artisan will appreciate that anysuitable inert gas can be supplied as a purge gas, and that the purgegas supply can be the continuous supply of the same inert gas used as acarrier gas in the previous precursor supply 110.

Subsequently, oxygen plasma is generated in-situ in the reactor (step130). In one embodiment, oxygen gas may be supplied to the reactorsubstantially continuously throughout the process described herein. Inanother embodiment, oxygen gas may be supplied to the reactor only atthe step 130. The plasma may be generated by applying plasma power (forexample, radio frequency power) to a capacitive coupling electrodepositioned in the reactor. The plasma power may have a frequency ofabout 13.56 MHz or about 27.12 MHz. In other embodiments, oxygen plasmamay be generated remotely and products of the plasma (e.g., excitedoxygen species or radicals) supplied to the reactor.

After generating the oxygen plasma (step 130), a purge gas, such as Ar,is supplied (step 140) into the reactor. The purge gas supplied at thestep 140 may be the same as the purge gas supplied at the step 120,which may also serve as carrier gases during the reactant pulses 110,130. A skilled artisan will appreciate that any suitable inert gas canbe supplied as a purge gas. In certain embodiments, the step 140 may beomitted, particularly where the active oxygen species of step 130quickly die off after stopping the plasma power supply.

The steps 110-140 described above may form a cycle, which may berepeated until a silicon oxide film having a desired thickness isdeposited on the substrate (decision box 150). In one embodiment, thisprocess can be performed at a process temperature between about 50° C.and about 450° C. and under a process pressure of about 0.1 torr toabout 10 torr. In one embodiment, oxygen (O₂) gas may have a gas flowrate between about 50 sccm and about 300 sccm. The plasma power appliedto the reactor for in situ plasma generation may be between about 50 Wand about 700 W, or between about 0.05 W/cm² and about 2 W/cm².

In Example 1, a silicon oxide film was deposited by a deposition methodaccording to the first embodiment. The process temperature was about350° C., and the process pressure was about 1.5 torr. The oxygen (O₂)flow rate was about 50 sccm, and plasma power applied was about 200 W.

FIG. 2 is a depth profile graph representing atomic emissionspectroscopy (AES) analysis results of the silicon oxide film. Thesilicon oxide film was found to have an atomic ratio of silicon (Si) tooxygen (O) of about 1:1. The silicon oxide film included less than 3atomic % of impurities, such as carbon (C) atoms and nitrogen (N) atoms.In other words, a silicon-rich silicon oxide film was formed by thedeposition method. The silicon-rich silicon oxide film according toembodiments described herein may have an atomic ratio of silicon (Si) tooxygen (O) of about 0.5:1 to about 1.1:1, or optionally about 0.55:1 toabout 1.1:1.

Referring to FIG. 3, the refractive indices (RI) of silicon oxide filmsformed by deposition methods will be described below. In Examples 2-Aand 2-B, silicon oxide films were formed by methods according to thefirst embodiment under different conditions. In Example 2-C, a siliconoxide film was formed by thermal ALD methods.

In Example 2-A, a first silicon oxide film was deposited usingSiH₂[N(C₂H₅)₂]₂ at a process temperature of about 250° C. and a processpressure of about 3 Torr with an oxygen (O₂) flow rate of about 100 sccmand applied plasma power of about 100 W. In Example 2-B, a secondsilicon oxide film was deposited using SiH₂[N(C₂H₅)₂]₂ at a processtemperature of about 350° C. and a process pressure of about 1.5 torrwith an oxygen (O₂) flow rate of about 200 sccm and plasma power ofabout 200 W. The second silicon oxide film deposited in Example 2-B hadsubstantially the same thickness as the first silicon oxide filmdeposited in Example 2-A. In addition, a third silicon oxide film havingsubstantially the same thickness as the silicon oxide films of Examples2-A and 2-B was deposited by thermal atomic layer deposition (ALD),using SiH₂[N(C₂H₅)₂]₂ and ozone (O₃) as reactants. The third siliconoxide film was deposited at a process temperature of about 300° C. and aprocess pressure of about 1.0 torr, while ozone was supplied at a flowrate of about 100 sccm.

The refractive indices (RI) of the first to third silicon oxide filmswere measured, and the results are shown in FIG. 3. The first siliconoxide film in Example 2-A was found to have an RI of about 1.459. Thesecond silicon oxide film in Example 2-B was found to have an RI ofabout 1.483. The third silicon oxide film deposited by the thermal ALDmethod was found to have an RI of about 1.457. Thus, the silicon oxidefilms in Examples 2-A and 2-B had RI greater than the silicon oxide filmdeposited by the thermal ALD method.

The silicon oxide films may have various RI values, depending on theplasma process conditions. However, the greater RI value is, the sloweris the etch rate of the silicon oxide film. In one embodiment, a siliconoxide film having a relatively high RI value may be used as a linerinsulation film used for formation of a shallow trench isolation (STI)structure in a semiconductor device. In such an embodiment, the siliconoxide film having a high RI value may prevent a moat from being producedat the edge of the STI structure during a wet etching process, sincesilicon-rich silicon oxide film is not wet-etched well.

In the first embodiment described above,N,N,N′,N′-tetraethyldiaminosilane (SiH₂[N(C₂H₅)₂]₂) may be used as asilicon precursor. N,N,N′,N′-tetraethyldiaminosilane (SiH₂[N(C₂H₅)₂]₂)has good deposition characteristics at a temperature between about 50°C. and about 450° C. Thus, deposition can be performed in a relativelywide temperature range with a relatively small amount of the precursor.In addition, N,N,N′,N′-tetraethyldiaminosilane has good thermalstability at a high process temperature (for example, about 350° C.)when used in the plasma enhanced atomic deposition method (PEALD)according to the first embodiment. Good thermal stability is importantfor self-limited behavior (and thus thickness uniformity) in ALDmethods, so that the precursor self-limitingly adsorbs rather thandecomposing during the silicon precursor pulse. Furthermore, a siliconoxide film having a desired atomic ratio may be formed, using theprecursor.

In addition, the deposition method according to the first embodimentforms a silicon oxide film having good step coverage while providing athin and/or uniform thickness over features having a high aspect ratio.

Referring to FIG. 4, a method of depositing a silicon oxide filmaccording to a second embodiment will be described below. FIG. 4illustrates gas supply cycles for the method.

In the illustrated method, a substrate on which a silicon oxide film isto be deposited is loaded into a reactor. The details of the substratecan be as described above with respect to the substrate of FIG. 1. Inone embodiment, the reactor may be a chemical vapor deposition (CVD)reactor. In another embodiment, the reactor may be an atomic layerdeposition (ALD) reactor. Examples of reactors include, but are notlimited to, those described in U.S. patent application Ser. No.12/058,364, filed on Mar. 28, 2008, entitled LATERAL FLOW DEPOSITIONAPPARATUS AND METHOD OF DEPOSITING FILM BY USING THE APPARATUS, thedisclosure of which is incorporated herein by reference in its entiretyfor purposes of describing a suitable reactor for implementing thesecond embodiment.

Then, a reactant gas R, such as ozone (O₃), is substantiallycontinuously supplied over the substrate in the reactor for a first timeperiod t1 and a second time period t2 in a first direction relative tothe orientation of the substrate. During the first time period t1, whilesupplying the reactant gas R, a silicon source gas S is also suppliedover the substrate in the first direction. The silicon source gas S mayinclude a diaminosilane compound represented by Formula 1 above. In oneembodiment, the silicon source gas S may beN,N,N′,N′-tetraethyldiaminosilane (SiH₂[N(C₂H₅)₂]₂).

During the second time period t2, the supply of the silicon source gasis stopped, the reactant R flow continues and a purge gas P is suppliedto the reactor in the first direction. The second time period t2 may beshorter than the first time period t1. In certain embodiments, thesecond time period t2 may be omitted. The steps performed during thefirst and second time periods t1, t2 form a first cycle, which can berepeated one or more times.

The reactant gas R, such as ozone (O₃), continues to be supplied to thereactor for a third time period t3 and a fourth time period t4. Duringthese periods, the reactant gas R may be supplied over the substrate ina second direction relative to the orientation of the substrate. Thesecond direction may be substantially different from the firstdirection. In one embodiment, the second direction is generally oppositefrom the first direction. In another embodiment, the first and seconddirections may be substantially perpendicular to each other. A skilledartisan will appreciate that an angle between the first and seconddirections can vary widely, depending on the deposition methods.

During the third time period t3, while supplying the reactant gas R, asilicon source gas S is supplied over the substrate in the seconddirection. Subsequently, during the fourth time period t4, a purge gas Pis supplied to the reactor in the second direction. The steps performedduring the third and fourth time periods t3, t4 form a second cycle,which can be repeated one or more times. One or more of first cycles andone or more of second cycles can form a super-cycle, which can berepeated until a silicon oxide film having a desired thickness is formedon the substrate.

In some embodiments, a super-cycle may include one or more of thirdcycles during which gases are supplied over the substrate in a thirddirection that is different from the first and second directions. Inother embodiments, a super-cycle may include additional cycles duringwhich gases are supplied over the substrate in directions that aredifferent from the first to third directions. Changing directions offlow, relative to the substrate, in a regular manner, allows averagingout any spatial non-uniformities, such as depletion effects andby-product interference with downstream deposition, thus improvingthickness and compositional non-uniformity. The different directions canbe accomplished by incremental rotation of the substrate or moving thesubstrate among multiple deposition zones into different orientationsrelative to the gas flow directions. Examples of changing directions offlow are described in detail in U.S. patent application Ser. No.12/058,364, the disclosure of which is incorporated herein by referencein its entirety.

In one embodiment, the method can be performed at a process temperaturebetween room temperature and about 400° C., optionally between about200° C. and about 350° C. The method can be performed under a processpressure between about 0.1 torr and about 10 torr, optionally betweenabout 1.5 torr and about 3 torr. The reactant gas R, such as ozone (O₃),may be supplied at a gas flow rate between about 50 sccm and about 1000sccm, optionally between about 250 sccm and about 1000 sccm.

In the illustrated method, the reactant gas R is substantiallycontinuously supplied to the reactor during one or more super-cycles.During the super-cycles, at least a portion of the reactant gas R isadsorbed on the surface of the substrate while additional reactant gas Rmay remain in the reactor. In addition, at least a portion of the sourcegas S supplied during the first time period t1 and the third time periodt3 is adsorbed on the surface of the substrate while the remainder ofthe supplied source gas S may remain in the reactor in vapor phase.

During the first time period t1 and/or the third time period t3, theremainders of the source gas S and the reactant gas R react with eachother to form a silicon oxide film by chemical vapor depositionreactions. Further, during the first time period t1 and the third timeperiod t3, the source gas S adsorbed on the surface of the substratereacts chemically with the reactant gas R on the heated surface of thesubstrate during the second time period t2 and the fourth time periodt4, and forms a silicon oxide film by atomic layer deposition reactions.In the illustrated embodiment, either or both of reaction ofsimultaneously supplied vapor phase reactants (CVD) and a surfacereaction of separately supplied reactants (ALD) may occur during eachcycle to form a silicon oxide film, thereby increasing the depositionrate.

In addition, the deposition method includes supplying the source gas Sand the reactant gas R in different directions relative to theorientation of the substrate. As described above, the deposition methodincludes the gas supplying time periods t1 and t2 during which thesource gas S, the reactant gas R, purge gas P are supplied in the firstdirection, relative to the substrate. The method also includes the gassupplying time period t3 and t4 during which the source gas S, thereactant gas R, and purge gas P are supplied in the second directiondifferent from the first direction, relative to the substrate. Thisconfiguration can increase the thickness uniformity of a silicon oxidefilm. In certain embodiments where a lateral flow deposition method isused, the embodiment can substantially improve the thickness uniformityof a silicon oxide film by averaging out any spatial non-uniformitiesdue to the CVD component of the reactions.

Examples of deposition methods according to the embodiments describedabove will be described. In Example 3, deposition was conductedaccording to the second embodiment described above with reference toFIG. 4. In Example 3, a gas supplying method included repeating thefirst and second cycles described above with reference to FIG. 4. InExample 3, each gas supplying super-cycle t1 to t4 included flowinggases in a first gas flow direction during t1 and t2 and in a second gasflow direction during t3 and t4. The second gas flow direction wasopposite to the first gas flow direction, relative to the substrate.

In Example 4, deposition was conducted according to the first embodimentdescribed above with reference to FIG. 1. In Example 4, a gas supplyingmethod included flowing gases only in a single flow direction relativeto the orientation of a substrate.

In Example 5, deposition was conducted by repeating supplying a sourcegas, a purge gas, a reactant gas, and a purge gas alternately inseparated pulses of a conventional ALD method. In Examples 3-5,deposition conditions were the same as one another except for the gassupplying methods.

In Examples 3 and 5, the deposition rates of the silicon oxide filmswere measured, and the results are shown in Table 1.

TABLE 1 Deposition Rate (Å/cycle) Example 3 2.5 Example 5 1.1

Table 1 shows that the silicon oxide film of Example 3 was deposited ata higher deposition rate than that of Example 5. The deposition rate ofExample 3 was more than twice greater than that of Example 5.

In Examples 3 and 4, the thickness uniformities of the silicon oxidefilms were measured, and the results are shown in FIGS. 5 and 6,respectively. The thicknesses of the silicon oxide films were measuredat 49 points on the top surfaces of the substrates by ellipsometry.

In Example 3, the average thickness of the silicon oxide film was about228 Å and the deviation (high/low variance) of the thickness was about5.76%. The standard deviation was 3.25%. In Example 4, the averagethickness of the silicon oxide film was about 155 Å and the deviation(high/low variance) of the thickness was about 13.83%. The standarddeviation was 6.93%. These results show that the silicon oxide film ofExample 3 has a more uniform thickness and a higher deposition rate thanthat of the silicon oxide film of Example 4.

Although embodiments and examples have been described, the presentinvention is not limited to the embodiments and examples, but may bemodified in various forms without departing from the scope of theappended claims, the detailed description, and the accompanying drawingsof the present invention. Therefore, it is natural that suchmodifications belong to the scope of the present invention.

1. A method of depositing a silicon oxide film over a substrate, themethod comprising one or more of deposition cycles, each of the cyclescomprising: supplying a plurality of pulses of silicon source gas of acompound represented by Formula 1 into a reactor in which a substrate isloaded,

wherein R is a straight or branched alkyl group having 1 to 4 carbons;and providing an oxygen-containing gas over the substrate in thereactor.
 2. The method of claim 1, wherein the compound comprises N, N,N′, N′-tetraethyldiaminosilane (SiH₂ [N(C₂H₅)₂]₂).
 3. The method ofclaim 1, wherein at least one of the cycles comprises providing theoxygen-containing gas after supplying the silicon source gas.
 4. Themethod of claim 3, wherein the at least one of the cycles furthercomprises supplying a purge gas into the reactor after supplying thesilicon source gas and before providing the oxygen-containing gas. 5.The method of claim 3, wherein the at least one of the cycles furthercomprises providing a purge gas into the reactor after providing theoxygen-containing gas.
 6. The method of claim 1, wherein providing theoxygen-containing gas comprises providing oxygen plasma.
 7. The methodof claim 6, wherein providing the oxygen plasma comprises generating theoxygen plasma in-situ in the reactor.
 8. The method of claim 7, whereingenerating the oxygen plasma comprises supplying oxygen gas into thereactor, and applying plasma power to the reactor to activate the oxygengas.
 9. The method of claim 8, wherein applying the plasma powercomprises applying plasma power between about 0.05 W/cm² and about 2W/cm².
 10. The method of claim 1, wherein the oxygen-containing gascomprises ozone.
 11. The method of claim 1, wherein at least one of thecycles comprises, in sequence: supplying the silicon source gas; andsupplying a purge gas into the reactor to purge the silicon source gasfrom the reactor.
 12. The method of claim 11, wherein the at least oneof the cycles comprises providing the oxygen-containing gassubstantially continuously throughout the at least one cycle.
 13. Themethod of claim 11, wherein the at least one of the cycles comprises:providing the oxygen-containing gas during supplying the silicon sourcegas; and providing the oxygen-containing gas during supplying the purgegas.
 14. The method of claim 13, wherein the one or more of depositioncycles comprise a first cycle and a second cycle, wherein the firstcycle comprises flowing at least one of the silicon source gas or theoxygen-containing gas in a first direction relative to the orientationof the substrate, and wherein the second cycle comprises flowing atleast one of the silicon source gas or the oxygen-containing gas in asecond direction relative to the orientation of the substrate, thesecond direction being different from the first direction.
 15. Themethod of claim 1, wherein each of the cycles is conducted at a processtemperature between room temperature and about 400° C.
 16. The method ofclaim 1, wherein each of the cycles is conducted at a process pressurebetween about 0.1 torr and about 10 torr.
 17. The method of claim 1,wherein providing the oxygen-containing gas comprises supplying theoxygen-containing gas at a gas flow rate between about 50 sccm and about300 sccm.
 18. The method of claim 1, wherein providing theoxygen-containing gas comprises supplying the oxygen-containing gas at agas flow rate between about 50 sccm and about 1000 sccm.
 19. Anapparatus comprising: a silicon oxide film made by the method of claim1, wherein the silieon oxide film has an atomic ratio of silicon tooxygen of about 1:1, and wherein the silicon oxide film has a refractiveindex between about 1.459 and about 1.483.
 20. A method of forming athin film over a substrate, the method comprising a first cycle whichcomprises: supplying a vapor phase silicon precursor comprisingdiaminosilane over a substrate; purging the vapor phase siliconprecursor from the substrate; and supplying ozone gas to the substrateduring supplying the vapor phase silicon precursor and after purging andbefore a subsequent cycle.
 21. The method of claim 20, wherein supplyingozone gas is conducted substantially continuously during the firstcycle.
 22. The method of claim 20, wherein the silicon precursor isrepresented by Formula 1:

wherein R is a straight or branched alkyl group having 1 to 4 carbons.23. The method of claim 22, wherein the silicon precursor comprises N,N, N′,N′-tetraethyldiaminosilane (SiH₂[N(C₂H₅)₂]₂).
 24. The method ofclaim 20, wherein the first cycle comprises flowing the precursor andthe ozone gas in a first direction relative to the orientation of thesubstrate.
 25. The method of claim 20, further comprising a second cyclewhich comprises: supplying the vapor phase silicon precursor over thesubstrate; purging the vapor phase silicon precursor from the substrate;and supplying ozone gas to the substrate during supplying the vaporphase silicon precursor, after purging and before a subsequent cycle,wherein the second cycle comprises flowing the precursor and the ozonegas in a second direction relative to the orientation of the substrate,the second direction being different from the first direction.
 26. Themethod of claim 25, wherein the first cycle comprises flowing purge gasin the first direction, and wherein the second cycle comprises flowingthe purge gas in the second direction.
 27. The method of claim 20,wherein the deposition rate of the silicon oxide film is more than about1.1 Å/cycle.
 28. A method of depositing a thin film over a substrate,the method comprising; supplying a silicon source gas to a substrate;and supplying an excited oxygen species to the substrate to form a film,such that the film has an atomic ratio of Si to O of about 0.5:1 toabout 1.1:1.